Non-physiological vaginal discharges in the sow can have both an urinary or a genital origin. Vaginal discharges syndrome with a genital origin is characterized by the appearance of vaginal losses related in time with farrowing or with mating. On the contrary, the appearance of vaginal discharges with an urinary origin are not related to the estrous cycle.

Both postfarrowing and postmating discharges are symptoms of a metritis or an endometritis caused by the introduction of bacteria into the uterus during farrowing, mating or insemination. Non pathogenic bacteria from vagina plus bacteria of foecal origin from the animal, from the environment, and from the hands of the technician, go into the uterus and develop the infection. This process is quicker if the natural defences of the animal are low at that moment.

The sow that becomes infected during farrowing will show abundant vaginal discharges during several days postpartum. If she does not recover during lactation its future fertility will be affected. The sow that becomes infected during mating or insemination will show vaginal discharges during the next proestrous, when it will be evident that she is not pregnant. If she cannot recover, she will present vaginal discharges in every proestrous.